{l_brace}XW{sub 12}O{sub 40} [Cu(en){sub 2}(H{sub 2}O)]{sub 3}{r_brace} (X=V, Si): Two novel tri-supported Keggin POMs with transition metal complexes

Two novel polyoxometalate derivatives, {l_brace}X{sup IV}W{sup VI}{sub 10}W{sup V}{sub 2}O{sub 40}[Cu(en){sub 2}(H{sub 2}O)]{sub 3}{r_brace} [X=V (1), Si (2); en=ethylenediamine], have been hydrothermally synthesized and characterized by elemental analyses, IR, UV-Vis, XPS, EPR, TG and single crystal X-ray diffraction analyses. They represent the first classical Keggin polyoxoanion supported by three transition metal complex moieties, which further act as the neutral molecular unit for the construction of the interesting three-dimensional supramolecular frameworks. The magnetic properties of 1 have also been studied in the temperature range of 4-300 K, and its magnetic susceptibility obeys the Curie-Weiss law, showing antiferromagnetic coupling. - Graphical abstract: The first classical Keggin polyoxoanion tri-supported by TMC moieties via bridge oxygen atoms, {l_brace}X{sup IV}W{sup VI}{sub 10}W{sup V}{sub 2}O{sub 40}[Cu(en){sub 2}(H{sub 2}O)]{sub 3}{r_brace}, act as the neutral molecular unit to construct the interesting 3-D supramolecular frameworks.